President Obama said he is unaware of longstanding efforts by Republican lawmakers to question survivors of the Benghazi attacks but pledged to investigate the issue.

“I’m not familiar with this notion that anybody has been blocked from testifying,” the president said during a White House news conference on Tuesday. “So what I’ll do is I will find out what exactly you’re referring to.”

Obama’s pledge to find out more came as officials at the State Department pushed back against allegations — first aired Monday on Fox News — that career employees at the agency have been threatened if they furnish new information about the Benghazi attacks to members of Congress.

“The State Department is deeply committed to meeting its obligation to protect employees, and the State Department would never tolerate — tolerate or sanction — retaliation against whistle-blowers on any issue, including this one,” spokesman Patrick Ventrell told reporters at a briefing on Tuesday. “That’s an obligation we take very seriously — full stop.”

Four Americans, including U.S. Ambassador to Libya Chris Stevens, were killed in terrorist attacks on U.S. installations in the port city of Benghazi, Libya, on the night of Sept. 11, 2012. While the FBI investigation into the attacks continues, no known instances of any perpetrators being brought to justice have yet been reported.

Rep. Darrell Issa, R-Calif., chairman of the House Oversight and Government Reform Committee, will hold the first in a new round of hearings on the subject on May 8. […]

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